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(defun yoba (z)
  (loop :for i :upto (integer-length z) :by 4
        :when (logbitp i z) :do
          (setf #1=(ldb (byte 4 i) z) (logxor #b1100 #1#)))
  z)

(defun main ()
  (loop :for z := (read *standard-input* nil) :while z :do
    (format t "~d (~:*~b) -> ~d (~:*~b)~%" z (yoba z))))

(main)
Success #stdin #stdout 0.02s 8288KB
comments (?)
stdin 
1 3434
42
stdout 
1 (1) -> 13 (1101)
3434 (110101101010) -> 362 (101101010)
42 (101010) -> 42 (101010)
https://ideone.com/iHtCOW
language:
Common Lisp (clisp 2.49.92)
created:
6 years ago
visibility:
secret

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